hdu 2674 N！Again

N！Again

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 1128 Accepted Submission(s): 631

Problem Description WhereIsHeroFrom:             Zty, what are you doing ? Zty:                                     I want to calculate N!...... WhereIsHeroFrom:             So easy! How big N is ? Zty:                                    1 <=N <=1000000000000000000000000000000000000000000000… WhereIsHeroFrom:             Oh! You must be crazy! Are you Fa Shao? Zty:                                     No. I haven's finished my saying. I just said I want to calculate N! mod 2009 Hint : 0! = 1, N! = N*(N-1)!

Input Each line will contain one integer N(0 <= N<=10^9). Process to end of file.

Output For each case, output N! mod 2009

Sample Input 4 5

Sample Output 24120

解题思路：水题，对于2009以前的部分打表，之后都是0了。

#include <iostream>

using namespace std;
int a[3000];
int main()
{
    int n,i;
    a[0] = 1;
    for(i=1;i<=2009;i++)
    {
        a[i] = a[i-1]*i%2009;
    }
    while(cin>>n)
    {
        if(n<=2009)
        cout << a[n]<<endl;
        else
            cout << '0'<<endl;

    }
    //cout << "Hello world!" << endl;
    return 0;
}